There are a few methods to install Git on a Mac. You can acquire it:

via the Installer

Download and install: git-osx-installer

via MacPorts

• Install MacPorts if you haven’t already done so.
• Make sure your ports are up to date.

$ sudo port selfupdate

MacPorts base version 1.600 installed

Downloaded MacPorts base version 1.600

The MacPorts installation is not outdated and so was not updated
selfupdate done!

• Install Git

$ sudo port install git-core
--->  Installing curl 7.18.2_0
--->  Activating curl 7.18.2_0
--->  Installing openssh 5.0p1_0+darwin_9
--->  Activating openssh 5.0p1_0+darwin_9
--->  Installing p5-error 0.17012_0
--->  Activating p5-error 0.17012_0
--->  Installing popt 1.13_0
--->  Activating popt 1.13_0
--->  Installing rsync 3.0.2_0
--->  Activating rsync 3.0.2_0
--->  Installing git-core 1.5.5.3_0+doc
--->  Activating git-core 1.5.5.3_0+doc

You may want to include Subversion support if you want to import SVN repositories.

via compiling manually

See compiling and installing git on mac os x.

Other Mac-related Git links

• GitHub Textmate Theme and Git bundle for TextMate
• More Textmate goodness